There is a lot to learn about Microsoft Dynamics CRM; although many have been tripped up by the ease in which you can configure and customize the system and the general marketing buzz. Don't let this fool you into thinking you are not still working with a powerful machine!
Dan Blake offers a primer on Microsoft Dynamics CRM Infrastructure multi-tenancy options. His post on this is now a year and a half old, but it still packs a mean punch with some great tidbits so if Multi-Tenancy is within your radar take a look.